1. Field of Invention
This invention relates generally to a two-way door latch whose knobs may be turned either clockwise or counterclockwise for retracting a latch bolt to open the door, and more particularly to a door latch of this type in which the knobs are normally maintained at a rest position, and when the latch is put in a privacy mode so that the knobs cannot be rotated, this mode is visually indicated.
2. Status of Prior Art
In a conventional door latch, the hinged door is provided adjacent its edge with an opening whose opposing ends are covered by escutcheons. Mounted on these escutcheons are two knobs which rotate about a common axis and are operatively coupled to a latch bolt assembly received in a bore in the edge of the door. The latch bolt is spring-biased so that it normally projects into a strike plate mounted over a cavity in the door jamb, thereby locking the door. When either knob is turned, the latch bolt is retracted from the strike plate and the door may then be swung open.
As used herein, the term knob refers to a rounded protuberance or a handle having an arm extension.
In the door latch disclosed in the Morgan U.S. Pat. No. 3,580,622, a single screw coaxial with the knob axis interconnects the escutcheons on opposite sides of the door to secure the escutcheons and the latch bolt assembly interlocked to the escutcheons in assembled relation. One of the knobs in the door latch may be shifted axially to engage the corresponding escutcheon so that the knob cannot then be rotated, thereby providing a privacy lock. In the Morgan latching arrangement, the knobs can only be turned in one direction-clockwise or counterclockwise-to unlatch the door.
In the two-way door latch arrangement disclosed in the Ramsey U.S. Pat. No. 3,792,886, the knobs may be turned either clockwise or counterclockwise for retracting the latch bolt. One of the knobs engages the related escutcheon when the knob is pushed towards the door to prevent rotation and provide a privacy lock. The escutcheon used in a privacy lock on the locking side of the door, say, inside a bathroom or bedroom, is referred to as the "locking" escutcheon. The escutcheon on the opposite side of the door is referred to as the "free" escutcheon. A pair of pins extend between the knobs and engage ramp elements in the latch bolt assembly which act to retract the bolt. A similar door latch is shown in the Ramsey U.S. Pat. No. 3,826,527.
The Ramsey U.S. Pat. No. 3,792,887 discloses a cylindrical patent bolt assembly insertable in a door edge so that it is in operative relation to a knob-operated door latch, the inner end of the spring-biased latch bolt having a pair of parallel legs each terminating in a ramp. When these elements are engaged by the operating mechanism of the door latch, the bolt is then retracted from the strike plate mounted in the door jamb.
The present invention is usable with any commercially available latch bolt assembly in which a spring-biased bolt cooperates with a pair of parallel legs, each terminating in a ramp, the ramp elements being engaged by a pair of pins which are offset with respect to the axis of rotation of the knob, such that when the knob is rotated, the pins travel in a circle concentric with this axis to cause the ramp elements engaged thereby to retract the latching bolt.